U.S. patent application number 10/414904 was filed with the patent office on 2004-12-09 for proxy support of mobile ip.
This patent application is currently assigned to M/A-COM Private Radio Systems, Inc.. Invention is credited to Roderique, William John.
Application Number | 20040249952 10/414904 |
Document ID | / |
Family ID | 33309501 |
Filed Date | 2004-12-09 |
United States Patent
Application |
20040249952 |
Kind Code |
A1 |
Roderique, William John |
December 9, 2004 |
Proxy support of mobile IP
Abstract
A proxy is utilized to limit the RF bandwidth needed for foreign
IP registration. An existing RF log-in procedure causes the proxy
to initiate and complete the foreign IP registration procedure with
the foreign agent at the RF site where the mobile node is located.
The proxy then acts as a locally connected (i.e., direct ethernet
connected) device for each IP address for which it is proxying, and
thus there is no need to use RF to register a mobile with the
active foreign agent. This allows the use of off-the-shelf home and
foreign agents to complete the mobile IP architecture, and reduces
the RF bandwidth used, since the RF portion of the registration
process (the registration between the active foreign agent and the
mobile) is reduced.
Inventors: |
Roderique, William John;
(Lynchburg, VA) |
Correspondence
Address: |
SYNNESTVEDT & LECHNER, LLP
2600 ARAMARK TOWER
1101 MARKET STREET
PHILADELPHIA
PA
191072950
|
Assignee: |
M/A-COM Private Radio Systems,
Inc.
Lynchburg
VA
|
Family ID: |
33309501 |
Appl. No.: |
10/414904 |
Filed: |
April 16, 2003 |
Current U.S.
Class: |
709/227 |
Current CPC
Class: |
H04L 29/06 20130101;
H04W 88/182 20130101; H04W 60/00 20130101 |
Class at
Publication: |
709/227 |
International
Class: |
G06F 015/16 |
Claims
What is claimed is:
1. A method of registering one or more mobile devices with a
foreign agent and home agent, comprising the steps of: providing a
proxy device between said foreign agent and said one or more mobile
devices; establishing a local connection between said proxy device
and said one or more mobile devices; and sending registration
messages from said proxy device to said home agent via said foreign
agent, on behalf of said one or mobile devices.
2. The method of claim 1, further comprising the step of:
establishing a local connection between said proxy device and any
mobile device that moves into operational range of said proxy
device.
3. The method of claim 2, further comprising the step of: sending a
de-registration message from said proxy device to said home agent
via said foreign agent, whenever a mobile device moves out of
operational range of said proxy device.
4. The method of claim 1, wherein said step of sending registration
messages includes at least the steps of: said proxy device building
a registration request on behalf of each mobile device generating a
login message that is received by said proxy device; said proxy
device sending said registration request to said foreign agent.
5. The method of claim 4, wherein said step of sending registration
messages further includes at least the step of: said foreign agent
building a database entry associating an identifier of each of said
one or more mobile devices with an address of said proxy device,
whereby any data from said home agent destined for one or more of
said mobile devices is directed to said proxy device via said
foreign agent based on said mobile device identifier.
6. A system for registering one or more mobile devices with a
foreign agent and home agent, comprising: a proxy device coupled
between said foreign agent and said one or more mobile devices,
said proxy device configured to: establish a local connection
between said proxy device and said one or more mobile devices; and
send registration messages from said proxy device to said home
agent via said foreign agent, on behalf of said one or mobile
devices.
7. The system of claim 6, wherein said proxy is further configured
to: establish a local connection between said proxy device and any
mobile device that moves into operational range of said proxy
device.
8. The system of claim 7, wherein said proxy device is further
configured to: send a de-registration message from said proxy
device to said home agent via said foreign agent, whenever a mobile
device moves out of operational range of said proxy device.
9. The system of claim 1, wherein said proxy device is further
configured to: build a registration request on behalf of each
mobile device generating a login message that is received by said
proxy device; and send said registration request to said foreign
agent.
10. The system of claim 9, wherein said foreign agent is configured
to: build a database entry associating an identifier of each of
said one or more mobile devices with an address of said proxy,
whereby any data from said home agent destined for one or more of
said mobile devices is directed to said proxy device via said
foreign agent based on said mobile device identifier.
11. A computer program product recorded on computer-readable medium
for registering one or more mobile devices with a foreign agent and
home agent using a proxy, comprising: computer-readable means for
establishing a local connection between said proxy and said one or
more mobile devices; and computer-readable means for sending
registration messages from said proxy to said home agent via said
foreign agent, on behalf of said one or mobile devices.
12. The computer program product of claim 11, further comprising:
computer-readable means for establishing a local connection between
said proxy and any mobile device that moves into operational range
of said proxy.
13. The computer program product of claim 12, further comprising:
computer-readable means for sending a de-registration message from
said proxy to said home agent via said foreign agent, whenever a
mobile device moves out of operational range of said proxy.
14. The computer program product of claim 11, wherein
computer-readable means for sending registration messages includes
at least: computer-readable means for building a registration
request on behalf of each mobile device generating a login message
that is received by said proxy; and computer-readable means for
sending said registration request to said foreign agent.
15. The computer-program product of claim 14, wherein said
computer-readable means for sending registration messages further
includes at least: computer-readable means for building a database
entry associating an identifier of each of said one or more mobile
devices with an address of said proxy, whereby any data from said
home agent destined for one or more of said mobile devices is
directed to said proxy via said foreign agent based on said mobile
device identifier.
Description
FIELD OF THE INVENTION
[0001] This invention is generally related to the field of two-way
radio communications, and more particularly, relates to mobile IP
networking via two-way radio communication systems.
BACKGROUND OF THE INVENTION
[0002] The definition of"mobile computing" has evolved, and
continues to evolve, in step with the advances that are occurring
in mobile communications. In the 1990's, mobile computing would
likely have described merely the use of a laptop computer. A laptop
computer gave the computer user the ability to easily transport a
keyboard, monitor, computer processor and memory from one location
to the next so that multiple desktop computers (e.g., one at the
office and one at home) were not necessary. Battery-powered laptop
computers made it possible for the user to operate the computer at
locations away from regular A/C power sources, such as on a plane
or train, or at a remote location (e.g., a construction work
site).
[0003] As computer networking developed, mobile computing took on a
slightly new meaning. With the ability to connect to an office
network using a modem and telephone line connection, a user was
able to access a centralized network from remote locations. Thus,
mobile computing could involve a laptop connected from a telephone
line in a hotel room in New York to a network system of a corporate
headquarters in Tokyo, Japan. The user could then disconnect the
telephone connection, travel to Chicago, set up the laptop in a
similar fashion and communication with the Tokyo office via a phone
line connection from a hotel room in Chicago.
[0004] Along the way, cellular telephony became commonplace. Using
cellular telephones, a user could travel from place to place with a
wireless connection to the telephone system, so that, regardless of
location, they could be reached at a single telephone number and
could carry on the communication while moving from one location to
another. It was only a matter of time before mobile computing would
seek to have the same kind of connectivity.
[0005] Today, mobile computing includes the continuous wireless
connectivity to an IP-based network with the ability to roam from
point A to point B while maintaining the connection and ability to
communicate over the connection. To assist in the development of
mobile IP, the Internet Engineering Task Force (IETF) developed and
continues to develop a set of protocols, referred to as "RFCs",
governing mobile IP operation. These protocols establish a system
for keeping track of mobile systems ("mobiles") in a wireless IP
network, allowing a mobile to change its "point of attachment" to
the network without losing its ability to communicate over the
network. The most recent RFC related to tracking mobiles in a
wireless IP network, RFC 3344, which updates and obsoletes RFC
3344, which updated and obsoleted RFC 2002.
[0006] These protocols, among other things, established a system
whereby each mobile node uses two IP addresses: a fixed home
address and a "care-of" address that changes at each new point of
attachment. Through the use of a router associated with the home
address (called a ("home agent") and routers associated with the
care-of addresses (called "foreign agents"), the location of the
mobile node can be established, and datagrams and other forms of
data destined for a particular mobile node at its fixed home
address can be forwarded to the care-of address that has been
associated with that fixed home address.
[0007] The system described in RFC 3344 is well known and operates
adequately. However, mobile IP, as it exists in the RFCs today,
requires that a registration procedure be performed by the roaming
IP device with the "active" foreign agent (the foreign agent with
which a particular roaming IP device is registered at a given
time). This registration process uses precious RF bandwidth.
Accordingly, it would be desirable to have a mobile IP system
whereby the use of RF bandwidth for registration is minimized.
SUMMARY OF THE INVENTION
[0008] In accordance with the present invention, a proxy is
utilized to limit the RF bandwidth needed for foreign IP
registration. An existing RF log-in procedure causes the proxy to
initiate and complete the foreign IP registration procedure with
the foreign agent at the RF site where the mobile node is located.
The proxy then acts as a locally connected (i.e., direct ethernet
connected) device for each IP address for which it is proxying, and
thus there is no need to use RF to register a mobile with the
active foreign agent. This allows the use of off-the-shelf home and
foreign agents to complete the mobile IP architecture, and reduces
the RF bandwidth used, since the RF portion of the registration
process (the registration between the active foreign agent and the
mobile) is reduced.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a functional block diagram illustrating the
architecture of the prior art;
[0010] FIG. 2 illustrates the architecture of the present
invention; and
[0011] FIGS. 3(a and b) is a flowchart illustrating an example of
the operations performed by the Mini-ME to achieve the benefits of
the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0012] FIG. 1 is a functional block diagram illustrating the
architecture of the prior art. As shown in FIG. 1, a host computer
102 is connected to the Internet 104 and provides content to users
of the Internet in a well-known manner. A home agent 106 is
connected to the wireless network (e.g., a EDACS network) 108.
[0013] A first RF site 110 includes a foreign agent 112 coupled to
the network 108 and a radio tower 114 for broadcasting datagrams or
other data to mobiles within range. In FIG. 1, a first mobile 116
and a second mobile 118 are illustrated as being within range of RF
tower 114. With the mobiles 116 and 118 within range of RF tower
114, foreign agent 112 is the active foreign agent with respect to
mobiles 116 and 118.
[0014] A second RF site 120 includes a foreign agent 122 coupled to
a radio tower 124. Mobile 118 is shown as progressing from RF site
110 to RF site 120, which will be described in more detail below.
RF site 120 also has a third mobile 126 located within the
broadcast range of RF tower 124. With mobile 126 within range of RF
tower 124, foreign agent 122 is the active foreign agent with
respect to mobile 126, and when mobile 118 gets within range of RF
tower 124, foreign agent 122 will become the active foreign agent
for mobile 118 and foreign agent 112 will cease to be its active
foreign agent.
[0015] For the purpose of this example it is assumed that mobile
118 begins at RF site 110. As is well known, under the protocol
established in RFC 3344 each mobile is assigned a home address
(referred to as an IP address) associated with its home agent. In
addition, a mobile connected to a foreign link acquires a "care-of"
address. The mobile IP must register the care-of address with its
home agent, using a message exchange defined by the mobile IP RFCs.
To prevent denial of service attacks, the registration messages are
required to be authenticated. The home agent "advertises"
reachability to the network-prefix of the mobile node's home
address, thus attracting packets that are destined to the mobile
node home address. The home agent intercepts these packets and
"tunnels" them to the care-of address that the mobile node
registered previously.
[0016] If we assume now that mobile 118 moves from its position at
RF site 110 to its position at RF site 120, upon making this move,
the mobile 118 must change its care-of address from the address of
foreign agent 112 to the address of foreign agent 122. This is
performed automatically when mobile 118 moves into range of RF
tower 124, as described below.
[0017] Mobile 118 initiates registration with foreign agent 122
when mobile 118 perceives the IP network change or when mobile 118
receives a foreign agent advertisement from foreign agent 122. In
the case of a network change, mobile 118 sends out a broadcast (RF)
message requesting foreign agent services, to which foreign agent
122 responds (RF) with a foreign agent advertisement.
[0018] In the case of an EDACS system, mobile 118 never sees
foreign agent advertisement messages nor does it see a network
change because foreign agent advertisements are not broadcast over
the RF and because mobile units never see the data traffic of other
mobile units. Instead, mobile 118 recognizes a network change when
the control channel frequency changes. This occurs when the
original frequency coming from tower 114 is lost and the new
frequency coming from tower 124 is located.
[0019] In either case, registrations continue with the mobile 118
sending a registration request (via RF) to foreign agent 122, which
can accept or deny the request for any of a number of known
reasons. If foreign agent 122 accepts the request, it creates an
entry that maps the IP address of mobile 118 with the machine
address (discussed below) of mobile 118 and then forwards the
request to home agent 106; otherwise foreign agent 122 sends a
"request rejection" (via RF) to mobile 118. After receiving the
request acceptance or request rejection, home agent 106 sends a
registration accept or reject to foreign agent 122 which forwards
the response to mobile 118 (via RF). If home agent 106 accepts the
registration request, it now forwards (tunnels) all traffic
destined to mobile 118 to foreign agent 122. The foreign agent 122
de-tunnels the traffic and attempts to deliver the IP datagram to
mobile 118 using the machine address previously databased.
[0020] Each mobile, when it first arrives at an RF site (and
optionally at regular intervals) must register with the RF site by
sending its LID (machine address) over the control channel (control
channel refers to both an RF frequency and hardware/software to
service radios that are camped on that frequency). This LID
registration (called a LID log-in) occurs as part of a prior art
process intended to support voice calls roaming about the EDACS
system.
[0021] When a mobile moves from one RF site to another RF site, it
performs a registration (log-in) with the new site. This
registration is typically quite simple. The mobile sends its LID to
the RF site in some technology-dependent fashion (for EDACS this is
done on the control channel on a LID log-in message).
[0022] In an EDACS system, the control channel is in charge of many
working channels. In other RF systems to which the present
invention applies, the control channel and working channel are
often one and the same (for example, TDMA systems where the
bandwidth of the channel is divided up between control and working
channels). The term "RF site" is intended to encompass either type
of system.
[0023] In prior art methods, the mobile performs the RF
registration process defined above and then has to send an IP
mobile registration message, via RF, to the RF site where it can be
converted to IP/Ethernet and delivered to the foreign agent
destined for the home agent. The RF site-to-foreign agent link and
the foreign agent-to-home agent link are IP over Ethernet (i.e., no
RF is used). Additionally, the home agent must acknowledge the
mobile by sending the registration reply back to the foreign agent
destined for the mobile. This uses RF to get from the RF base
station to the mobile.
[0024] In a worst-case scenario, if the mobile is not in sync
(time-wise) with the home agent, the mobile will send a
registration to the home agent only to be rejected by the home
agent, which sends back the correct time value so that the mobile
can be synchronized. The mobile then re-requests registration using
the new time synchronization value. Once the two are synchronized,
the home agent accepts the registration, assuming everything else
is okay. Thus, in the best-case scenario, the prior art system uses
three RF communications for registration, and in the worst-case
scenario, the prior art uses five RF communications.
[0025] FIG. 2 illustrates the architecture of the present
invention. As can be seen in FIG. 2, each foreign agent has a
proxy, in this example, a Miniature Mobility Exchange (Mini-ME),
associated therewith. Specifically, as seen in FIG. 2, site 110 has
a Mini-ME 211 coupled between RF tower 114 and foreign agent 112.
Similarly, site 120 includes a Mini-ME 221 situated between RF
tower 124 and foreign agent 122.
[0026] The MME is a logical entity that could be software or
hardware and could be implemented on a number of platforms. For
instance, one alternate configuration places the MME on the
hardware and as part of the software that makes uf the EDACS
control channel.
[0027] The important aspects that comprise the MME are (1) the MME
maintains a table of IP-Address-to-mobile-physical-address
mappings, a table of IP-Address-to-Home-Agent mappings, and the IP
address of the Foreign Agent (FA); (2) the MME has an IP connection
over some physical medium to the FA; (3) the MME has some physical
connection to the RF site such that it can request or otherwise
indicate the destination mobile for a received IP datagram and such
that it can deliver that IP datagram to the RF site for subsequent
delivery to the mobile; (4) the MME can place IP Mobile
Registrations and accept IP Mobile Replys; and (5) the MME has
access to IP datagrams received such that it can inspect whether
the datagram is destined for one of the mobiles for which the MME
is a proxy.
[0028] The invention has been implemented in an EDACS system using
a PowerPC architecture with AMD fast Ethernet controller hardware,
and a Nucleus operating system. Of course, it is understood that
the invention is not limited to this implementation and numerous
other suitable implementations will be apparent to one of ordinary
skill in the art.
[0029] The MME uses its link to the RF site to determine when a
mobile has roamed into its coverage area. The MME looks up the
physical address (LID) of the mobile in its table of
IP-Address-to-mobile-physical-address mappings. If found, the MME
sends a registration to the Home Agent (HA) associated with that
particular mobile. The MME inspects all IP datagrams received to
see if they are destined for one of the mobiles for which it is a
proxy. When such datagram arrives, the MME uses its link to the RF
site to indicate that there is data available for a particular
mobile. The MME uses its link to the RF site to deliver the
datagram.
[0030] In accordance with the present invention, when a mobile
attempts a LID log-in over the control channel, the Mini-ME taps
into an existing communication between the control channel and
other equipment, i.e., the Mini-ME passively "sees" all LID log-ins
from mobile devices at the site. For an EDACS system, this is
accomplished by listening to the broadcast messages that the
Control Channel sends out to the other site equipment.
Specifically, there is a message called "login acknowledge" that
the MME keys off of. However, if the MME were in the alternate
configuration described previously, it would be part of the control
channel and would have software access to the messages being
received from the radio. Another configuration could have the MME
listening to the control channel frequency to see the mobiles
registering with the RF Site.
[0031] The site equipment (control channel--working
channel--Mini-ME- etc.) are connected and communicate via an
ethernet LAN. For EDACS systems, the Control Channel, Working
Channel, and MME all physically reside together at the RF site.
They are connected by a link called the Site LAN. The Call Trunking
LAN (CTL) is a logical subset of the messaging that occurs on the
Site LAN. The FA also resides at the RF site and is connected to
the MME via a link called the Management/Data LAN. In a preferred
embodiment, this communication is carried out via a "Control
Trunking LAN" or CTL, but it is understood that any type of
connection can be used to perform this function, including software
interprocess communication, serial links, etc.
[0032] The RF logins are broadcast from the control channel
(hardware) to all devices on the LAN (including the Mini-ME) via
the CTL protocol. The Mini-ME then looks up in a configured
IP-Address-to-mobile-physical-addre- ss mapping table the IP
address associated with the LID that just logged in; looks up in a
configured IP-Address-to-Home Agent mapping table the home agent
for that IP address; and registers the IP address with the home
agent via the Mini-ME's associated foreign agent. The home agent,
from that point forward, tunnels all datagrams targeted to the
mobile IP's address to the foreign agent, which detunnels them and
delivers them to the Mini-ME. The foreign agent "thinks" that the
Mini-ME is actually the mobile, because the Mini-ME originated the
registration process on behalf of the mobile and it is the Mini-ME
machine address that the foreign agent has associated with the
mobile's IP address.
[0033] The Mini-ME requests a working channel from the control
channel for a call between itself and the mobile. The control
channel then informs the mobile and the Mini-ME of the assigned
working channel and the Mini-ME forwards the datagram to the mobile
via the working channel. As the mobile moves from site to site, it
must re-register with its home agent, even if it has nothing to
send. This is necessary because the host computer may have
something to send the mobile. However, no working channels are
necessary to log a mobile into an RF site. Mobiles login into the
site via the control channel message only.
[0034] To summarize the registration process when a mobile moves
into range of a new Mini-ME, each time that a mobile moves into the
"jurisdiction" of a particular Mini-ME, the Mini-ME registers with
the home agent of the mobile via the foreign agent associated with
the Mini-ME. This creates a tunnel from the home agent to the
foreign agent, so that data intended for the newly-arrived mobile
will make its way to the correct foreign agent. The foreign agent
already has a connection to the Mini-ME, so there is no need to
reestablish a connection between the foreign agent and the Mini-ME.
Further, since the Mini-ME has a "local connection" with the
newly-arrived mobile, there is no need to use RF for IP mobility
registration.
[0035] The Mini-ME performs this IP mobility registration process
with the appropriate home agent each time a mobile enters or leaves
its jurisdiction. Each time that a mobile moves into the
jurisdiction of a particular Mini-ME, the Mini-ME registers with
the home agent of the mobile via the foreign agent associated with
the Mini-ME, thereby updating the home agent with the mobile's new
foreign agent (i.e., location). The foreign agent treats the
Mini-ME as though it were the mobile and thus delivers any
forwarded (tunneled) packets destined to the mobile to the Mini-ME
instead.
[0036] The registration process between the Mini-ME and the home
agent via the foreign agent does not require the use of RF. The
registration process between the Mini-ME and the mobile is
accomplished via the pre-existing RF "local connection"
registration so no additional RF needs to be used. This is in
contrast to the prior art, which requires that each mobile register
with the appropriate foreign agent when it enters the foreign
agent's jurisdiction (using RF) in addition to performing any
required RF "local connection" registration. Thus, the present
invention cuts down on the use of RF, because the prior need to use
RF between the mobiles and the foreign agents to register them when
they move is no longer needed; only a single RF communication is
needed to complete registration.
[0037] The Mini-ME is looking for the mobile identifiers being sent
to the RF site. More accurately, the Mini-ME is looking at the
output from the site that acknowledges the identifier (e.g., the
LID). In EDACS, the control channel outputs each ID, which logs in
onto the Ethernet LAN in a proprietary message. The Mini-ME is
looking at these proprietary messages. In a more generic system to
which this patent also applies, the Mini-ME would listen to the RF
itself. In either case, the Mini-ME now has the RF-specific ID of
the mobile.
[0038] The Mini-ME is also configured with the database that
converts an RF-specific ID to an IP address. This allows the
Mini-ME to obtain the correct IP address for registering with the
home agent. The remainder of the registration process takes place
via IP over Ethernet, meaning no RF is used.
[0039] Without the Mini-ME, movement to a new site and the
re-registration associated therewith requires bringing up a working
channel and communicating via the foreign agent to the home agent,
assuming that the mobile even knows the IP address of the foreign
agent. If, as is usually the case, the mobile doesn't know the
foreign agent's IP address, then per the mobile IP RFC, the mobile
would typically broadcast out a request (advertisement) for a
foreign agent when it first arrived at a new RF site. The foreign
agent would then respond with its IP address, after which the
mobile could make the request of the home agent via the foreign
agent for service. Thus, in the prior art systems, each time a
mobile moves to a new site, three RF working channel calls are
potentially required, plus the original LID log-in.
[0040] FIG. 3 is a flowchart illustrating an example of the
operations performed by the Mini-ME to achieve the benefits of the
present invention. Referring to FIG. 3, at step 300, the Mini-ME
monitors the CTL for LID log-in messages. This process is
constantly occurring in accordance with the present invention.
[0041] At step 302, upon receipt of a LID log-in message, the
process proceeds to step 304 where it is determined if the LID
log-in received is configured for roaming data. This is determined
by looking in the Mini-ME configuration. If the LID does not exist
in the Mini-ME configuration, then the LID is not configured for
roaming data, and the process proceeds to step 306 where the log-in
is ignored and the process continues to monitor the CTL for LID
log-in messages.
[0042] If at step 304, however, it is determined that the LID
log-in is configured for roaming data, then at step 308, the
Mini-ME builds an IP mobile registration request (CRFC 3344) on
behalf of the mobile submitting the LID log-in. The building of the
IP mobile registration requires includes the filling in of the
import fields of the request as follows:
[0043] "Home Address" is set to the mobile's IP address;
[0044] "Home Agent" is retrieved from an internal database using
"Home Address" as a key;
[0045] "Care-of Address" is retrieved from the Mini-ME
configuration or obtained via agent advertisement messages per
prior art; and
[0046] "Authentication Extension" fields are also retrieved from an
internal database using "Home Address" as a key. The MME is
configured via the command line interface (CLI). This is a serial
or telnet connection. The configuration information is then stored
in non-volatile memory on the MME. A System Administrator or
Designer can decide on the IP Address scheme to use that maps the
LIDs to IP Addresses for all planned users of the EDACS RF System.
This Designer also must decide and configure which Home Agent(s)
handle which IP Addresses, etc. The CLI is then used to configure
these into the MME.
[0047] After filling in the fields of the IP mobile registration
request, at step 310, the Mini-ME sends the IP mobile registration
request to the foreign agent (at the IP Address configured into the
MME via CLI). The IP Header Source Address is set to the mobile's
IP address. However, because the Mini-ME originates the message,
the machine address of the Ethernet Frame that arrives at the
foreign agent is that of the Mini-ME.
[0048] At step 312, the foreign agent builds a database entry
associating the Source IP Address of the mobile with the machine
address of the Mini-ME, and then at step 314, the registration
proceeds.
[0049] At step 316, when the Mini-ME receives a datagram, a
determination is made (at step 318) as to whether or not the
destination IP address is configured for roaming data. If the
destination IP address is not configured for roaming data, the
process proceeds to step 320 to determine if the destination IP
address is the same as that of the Mini-ME. If, at step 320, it is
determined that the destination IP address is not that of the
Mini-ME, then the process proceeds to step 322 where the datagram
is discarded and then the process proceeds back to step 300 where
the Mini-ME monitors the CTL for LID log-in messages.
[0050] If, at step 320, it is determined that the destination IP
address is the address of the Mini-ME, then at step 334 a normal IP
Protocol Stack operation is performed, i.e., some other application
on the MME is receiving a message.
[0051] If, at step 318, it was determined that the destination IP
address is configured for roaming data, then the process proceeds
to step 324, where the Mini-ME uses the mobile IP address to
retrieve the LID. At step 326, a determination is made as to
whether or not the LID is already involved in an active call. This
is determined by checking the active call database. The MME builds
the Active Call Database over time. It starts out empty; when an IP
datagram is received, a destination entry is added with a status of
"call requested." A call request is made of the control channel and
when a reply is received (called a "channel assignment" message),
the status (if successful) is changed to "in program" and a working
channel number (received in the channel assignment message) is
added to the entry. The entry is deleted when a "channel drop"
message is received. If the LID is already involved in an active
call, then the datagram is forwarded to the correct working channel
as specified in the active call database. If, at step 326 it is
determined that the LID is not already involved in an active call,
then at step 330, the call is initiated by signaling the control
channel via a CTL, and then, when the control channel assigns a
working channel to the call, at step 332, the datagram is forwarded
to the working channel. Once this has been completed, the process
proceeds back to step 300 for continual monitoring of the CTL for
LID log-in messages.
[0052] The above-described steps can be implemented using standard
well-known programming techniques. The novelty of the
above-described embodiment lies not in the specific programming
techniques but in the use of the steps described to achieve the
described results. Software programming code which embodies the
present invention is typically stored in permanent storage of some
type, such as permanent storage of a proxy device such as a MiniME.
In a client/server environment, such software programming code may
be stored with storage associated with a server. The software
programming code may be embodied on any of a variety of known media
for use with a data processing system, such as a diskette, or hard
drive, or CD-ROM. The code may be distributed on such media, or may
be distributed to users from the memory or storage of one computer
system over a network of some type to other computer systems for
use by users of such other systems. The techniques and methods for
embodying software program code on physical media and/or
distributing software code via networks are well known and will not
be further discussed herein.
[0053] Using the above-described process, the number of RF working
channels required to be used are minimized, thereby maximizing the
efficiency of operation of the entire system.
[0054] It should be understood that the foregoing is illustrative
and not limiting and that obvious modifications may be made by
those skilled in the art without departing from the spirit of the
invention. Accordingly, the specification is intended to cover such
alternatives, modifications, and equivalence as may be included
within the spirit and scope of the invention as defined in the
following claims.
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